Refactor jQuery dropdown implementation to GitLab UI GlDropdown in blob/template_selector.js
The following component utilizes our old deprecated jQuery-based dropdown implementation and should be replaced with a new implementation based upon GitLab UI's `GlDropdown` component:
## DRAFT IMPLEMENTATION ALREADY EXISTS
Files affected:
- app/assets/javascripts/blob/template_selector.js
- app/assets/javascripts/blob/template_selectors/metrics_dashboard_selector.js
- app/assets/javascripts/blob/template_selectors/ci_yaml_selector.js
- app/assets/javascripts/blob/template_selectors/dockerfile_selector.js
- app/assets/javascripts/blob/template_selectors/gitignore_selector.js
- app/assets/javascripts/blob/template_selectors/license_selector.js
- app/assets/javascripts/blob/template_selectors/type_selector.js
- app/views/projects/blob/_template_selectors.html.haml
## DRAFT IMPLEMENTATION – feel free to pick it up: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/96337
issue